Loom

ABSTRACT

The invention relates to a loom comprising a warp thread tensioning device and a shedding device ( 12 ), which comprises pre-tensioned warp threads ( 4 ) in a first shedding position (F 1 ). The loom also comprises a lifting device ( 38 ), which can be driven in an oscillating manner, and followers ( 40 ) for the warp threads ( 4 ), in addition to control means ( 46 ) that can be operated by actuators ( 44 ) in order to selectively engage the warp threads ( 4 ) in the followers ( 40 ) and that displace the warp threads ( 4 ) into a second shedding position (F 3 ). To simplify said loom, a second lifting device ( 48 ), which is common to all warp threads ( 4 ), is provided in order to displace said warp threads ( 4 ) from the first shedding position (F 1 ) into a selection position (F 2 ), in which the first lifting device ( 38 ) is active, and in order to displace non-selected warp threads in unison into the first shedding position (F 1 ) by the pre-tensioning of said warp threads ( 4 ).

This application claims priority of PCT application PCT/CH2004/000337having a priority date of Jun. 12, 2003, the disclosure of which ishereby incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to a loom.

BACKGROUND OF THE INVENTION

A loom of the type initially mentioned is known from WO 99/13145. Theloom contains a warp thread tensioning device and a shedding devicewhich has warp threads pretensioned into a first shedding position. Alifting device capable of being driven in oscillation is equipped withdrivers for the warp threads, there being control means actuable bymeans of actuators, in order to bring the warp threads selectively intoengagement with the drivers which move the warp threads into a secondshedding position. There is the disadvantage that, in this loom, thelifting device equipped with the drivers has to move along the entiretravel of the warp threads from the first shedding position as far asthe second shedding position. The lifting device therefore has toexecute a relatively long travel, which, on the one hand, istime-consuming and, on the other hand, requires higher drive forces. Inorder to avoid this, in WO 99/13145 there is a further exemplaryembodiment, in which the warp threads assume a middle shedding positionand there are two lifting devices which each have drivers in order tomove the warp threads either into the top shedding position or into thebottom shedding position. This requires double the number of drivers,with the result that such a design variant is highly complicated andconsequently cost-intensive.

SUMMARY OF THE INVENTION

The object of the invention is to improve a loom of the type initiallymentioned.

The set object is achieved by means of the characterizing features ofclaim 1. Since the loom has a second lifting device which is common toall the warp threads and which moves the warp threads out of the firstshedding position into a switching position effective for the firstlifting device, this results, for all the warp threads, in a very simplesecond lifting device which, moreover, appreciably reduces the switchingtravel for the first lifting device, so that the first lifting devicehas to move a warp thread only out of the switching position into thesecond shedding position. Both lifting devices have to execute only alimited travel for which they require less time.

Moreover, since the lifting devices can be active simultaneously, anappreciable increase in the performance of the loom is obtained. Inaddition, owing to this design, the useful life is also improved owingto the lower susceptibility to wear. The loom also results in lowernoise emission. Advantageous refinements of the loom are describedbelow.

The second lifting device may be a lifting beam extending over all thewarp threads. The lifting travel of the second lifting device may varygreatly, and it is advantageous if, the latter executes at least halfthe lifting travel of the warp threads in the shed.

For the design of the first lifting device, there are various designvariants which are already contained in WO 99/13145. An embodiment thatis particularly advantageous, includes a first lifting device which hasfor each warp thread a control drop wire with a driver slot and anassigned driver, preferably of hook-shaped design, for the associatedwarp thread. The warp thread can be brought selectively into engagementwith the driver by means of a control drop wire switchable by means ofthe actuator. In some embodiments, the driver slot is assigned to thedisplacement path of the driver and, in the switching region, is guided,via a control slot running obliquely with respect to the direction ofdisplacement of the driver, out of the displacement path of the driverinto a widened guide slot of the control drop wire. To facilitate theintroduction of the warp thread into the control slot, the guide slot isprovided with a run-on side.

In principle, the control drop wire may be configured as a sheet steelstrip. In one advantageous design, the control drop wire is formed inthe shape of a sleeve with two side walls, between which the driver ismounted displaceably. A reliable guidance of the warp thread from and tothe driver is thereby achieved. To protect the warp thread, on the onehand, and to facilitate the run of the warp thread through the controldrop wire, on the other hand, at least the guide slot and the controlslot are offset relative to one another in the two side walls of thecontrol drop wire in the direction of run of the warp thread, in such away that a deflection of the running warp thread in the control dropwire is lower than 90°, preferably 10°.

There are various possibilities for driving the drivers, there beingpreference, for all the drivers of a row to be movable up and down bymeans of a common lifting knife. This affords a particularly simple andcost-effective solution.

Since the warp threads are moved in each case out of a first sheddingposition into the second shedding position, their displacement travel issuch that the elasticity of the warp thread is not sufficient, as arule, to ensure satisfactory functioning. It is therefore advantageousif, the warp thread tensioning device has an individual thread tensionerfor each warp thread on the run-in side of the warp threads to theshedding device. The tension of the individual warp thread can therebybe adapted more closely to the respective position of the warp thread inthe shed. The loom may have the conventional additional catch threaddevices. It is more advantageous, however, if, the thread tensioner isat the same time also designed as a catch thread device.

In some embodiments, each warp thread is guided via two guide elementswhich are arranged at a distance from one another and between which isarranged the thread tensioner which engages on the warp thread andexerts a pretension on the warp thread. The pretension may be generatedby a tensioning weight. In a more advantageous design, the pretension isgenerated by a tensioning spring. This also makes it possible, inparticular, to arrange the thread tensioner in a position deviating fromthe vertical.

The thread tensioner may be provided with a closed eye. In a moreadvantageous design however, each thread tensioner has a lateral run-ineye for the warp thread. In some embodiments, each thread tensioner isprovided with a guide orifice, by means of which it is mounted on aholder displaceably in the tensioning direction. Expediently, the threadtensioner is provided, in the direction opposite to the pretensioningdirection, with a grip part which preferably has a signal partprojecting out of the direction of displacement. Such a signal part maybe, for example, a projecting head part of the thread tensioner. As aresult, a thread tensioner on which a thread fault has occurred can bedetected more easily, since it emerges from the plane of the threadtensioners which are operating satisfactorily.

It is particularly expedient if, the thread tensioner is arranged on aholder which has a middle contact part which projects on one side andwhich, insulated, is embedded into lateral contact parts cooperatingwith the sides of the guide orifice of the thread tensioner. In theevent of a faulty warp thread tension, the contact parts come into touchwith an end face of the guide orifice, this touch bridging the contactsand thus triggering a fault signal.

The thread tensioner can be used in the most diverse possible looms. Itis preferably used, however, in a loom in which the warp threadtensioning device has a control device which is connected to the driveof a cloth take-up in such a way as to control the warp beam such thatthe warp threads as a whole are under a predeterminable tension force.The retaining force may be generated by means of a braking device at thewarp let-off. To generate the retaining force in a more advantageousembodiment, the warp beam is provided with specific drive which containsa selflocking gear. The warp thread tensioning device can be furtherimproved by means of the design, according to which it has a back bearerfor the warp threads which is pretensioned by means of a tensioningspring device. The tensioning spring device is connected to the controldevice, so that the drives of the warp beam and of the cloth take-up canbe controlled in such a way that the predeterminable tension force ismaintained at the back bearer. Various variants may be envisaged for thedesign of the tensioning spring device. In a particularly advantageousembodiment, the tensioning spring device has a leaf spring with aflexion converter which delivers corresponding control signals to thecontrol device. In addition, the warp thread tensioning device may bedesigned with a safety device which is operatively connected to the backbearer and which contains an emergency switch which responds when theforce of the warp threads which occurs in the back bearer is greaterthan the set tension force by a determinable safety amount.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the invention are described in more detailbelow with reference to the drawings in which:

FIG. 1 shows a diagram of a loom in a side view;

FIG. 2 shows a detail of the shedding device of the loom of FIG. 1 on alarger scale;

FIG. 3 shows the shedding device of FIG. 2 in the section III-III;

FIGS. 4-8 show various work stages of the shedding device of FIG. 2;

FIG. 9 shows the diagram of a further loom with individual threadtensioners in a side view;

FIG. 10 shows the thread tensioner of the loom according to FIG. 9 on alarger scale, and

FIG. 11 shows a detail of the device according to FIG. 10.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows diagrammatically a loom which, in general, has a warplet-off 2 which is designed, for example, as a warp beam, from whichwarp threads 4 arrive at the shedding device 12 via a back bearer 6,individual thread tensioners 8 and catch thread devices 10. In theshedding device 12, the warp threads 4 are opened to form a shed 14 intowhich can then be introduced a weft thread 16 which is beaten up at thebeating-up edge 18, so that a cloth web 20 is obtained. The cloth web20, held by a cloth holder 22, is taken up via a cloth take-up 24. Acontrol device 26 serves for controlling the loom.

The loom is provided with a thread tensioning device which primarilycontains the cloth take-up 24, the drive 28 of which is controlled bymeans of the control device 26 such that a predeterminable tension forcecommon to all the warp threads 4 is given as a function of the retainingforce of the warp let-off 2. The retaining force of the warp let-off maybe generated by means of a braking device 29 or a specific drive, inwhich a motor is connected to the warp let-off via a selflocking gear.The warp thread tensioning device additionally contains, for each warpthread 4, an individual warp thread tensioner 8 which is arrangedbetween two guide elements 30 and, in the example shown, individuallypretensions, by means of a pretensioning spring 32, the warp thread 4which runs through an eye 34.

In the shedding device 12, the warp threads 4 are pretensioned into afirst shedding position F₁ between a deflecting roller 36 and a clothholder 22 which may also be designed as an expander. A first liftingdevice 38 serves for the individual control of the warp threads 4, saidlifting device having drivers 40 which can be moved out of a switchingposition F₂ into the second shedding position F₃ by means of a liftingbeam 42. With the aid of control means 46 controllable by actuators 44,the warp threads 4 can be brought selectively into engagement with thedrivers 40 when the warp threads have been moved out of the firstshedding position F₁ into the switching position F₂ by means of a commonsecond lifting device 48, as is evident in detail in FIGS. 1 to 8. Thecontrol means 46 contain control drop wires 50 which are pretensioned bymeans of a pretensioning spring 52 against a lifting beam 54 on whichthey stand via a stop 56. The actuators 44 contain hook parts 58 whichcooperate with hook parts 60 on the control drop wires 50 and, in theactivated state, hold the control drop wire 50 in the lifted position. Anonactivated actuator 44 enables the displacement travel of the controldrop wire 50. In FIG. 1, each control drop wire 50 is symbolized by itsswitching travel, as illustrated in detail by means of FIGS. 2 to 8.Thus, the control drop wires contain a driver slot 62 which lies in thedisplacement travel of the warp thread 2. The driver slot has adjoiningit upwardly a control slot 64 which guides the warp thread out of thedisplacement travel of the driver into a widened guide slot 66, so thatit can no longer be grasped by the driver 40.

As may be gathered from FIGS. 2 and 3, the control drop wire is designedin the form of a sleeve and has side walls 68, 70 which are connected bymeans of end walls 72, 74 and which thus provide a cavity in which thedriver 40 is mounted displaceably. In particular, the driver slots 62 aand 62 b are arranged in the side walls 68, 70 so as to be offset in thedirection of run of the thread in such a way that the warp thread, whenit passes through the control drop wire, is inclined at an angle α fromthe vertical with respect to the control drop wire which is smaller than90°, preferably 40°, in order to keep as low as possible the passageresistance of the warp thread through the control drop wire andconsequently the wear of the warp thread, on the one hand, and of thecontrol drop wire, on the other hand.

The functioning of the shedding device is illustrated in more detailwith reference to FIG. 1 in conjunction with FIGS. 2 to 8. When thecontrol drop wire is in the lifted position, in which it is retained onthe actuator, as may be gathered from FIG. 1 for the actuator on theright and from FIGS. 2, 4 and 5, the warp thread is guided by means ofthe second lifting device 40 out of the guide slot 66 via an obliquerun-on side 76 into the control slot 64 and by means of the latter intothe driver slot 62 in which the warp thread lies in the displacementtravel of the driver 40. During the downward movement of the driver 40,the warp thread 4 is driven by the hook 40 a of the driver 40 out of theswitching position F₂ into the second shedding position F₃ which is thebottom shedding position. As long as the control drop wire 50 remains inthe lifted state, the warp thread 4 is moved to and fro by the amount ofthe height H1 only between the switching position F₂ and the bottomshedding position F₃, as is evident from FIGS. 2 and 4 to 6.

As soon as the actuator 44 releases the control drop wire 50 and thelatter is lowered by the amount of the switching quantity S, during theupward movement of the driver 40 the warp thread passes via the controlslot 64 into the widened guide slot 66 and consequently outside thedisplacement travel of the driver 40. Then, as may be gathered fromFIGS. 7 and 8, the warp thread passes again into the displacement travelof the second lifting device 48 and is moved over the height H2 out ofthe switching position into the first shedding position F₁ which is thetop shedding position.

FIG. 9 shows a loom with a special design of the warp thread tensioningdevice and of the thread tensioners, which loom may have, for example, ashedding device according to the loom of FIG. 1. The loom contains awarp beam 2 a, from which warp threads 4 are guided via a back bearer 6a to individual thread tensioners 8 a which are arranged upstream of ashedding device 12 a. The shedding device 12 a may be designed similarlyto the shedding device 12 of the loom of FIG. 1, but may also have otherdesigns. The cloth web 20 produced is taken up via a cloth take-up 24 aand wound up on a cloth beam 80. The loom contains a control device 26 awhich is designed, in particular, for controlling the warp threadtensioning device. The warp beam 2 a is actuated by a drive 82 which hasa selflocking gear 84. The drive is controlled by the control device 26a, specifically as a function of the drive 28 a of the cloth take-up 24a and of a tensioning spring device 86 with which the back bearer 6 astands against the warp threads 4. The control is such that the clothtake-up 24 a is set as a function of the retaining force of the drive 82of the warp beam 2 a such that a predetermined tension force can bemaintained at the back bearer 6 a.

The warp beam 6 a is fastened to a rocker 88 which is supported via asupporting device 90 on a leaf spring 92 provided with a flexionconverter 94 which transfers its data to the control device 26 a. Thesupporting device 90 comprises a safety device 96 containing a screwbolt 98, the head 100 of which is arranged displaceably in a holdingbell 102. The holding bell 102 is connected to the rocker 88. The head100 is supported on a stop 104 of the holding bell. A pretensioningspring 106 arranged outside the holding bell 102 is supported, on theone hand, on the screw bolt 98 via a setscrew 108 and on the holdingbell 102 via a washer 110 on the other hand so that the head 100 bearswith a corresponding pretensioning force against the stop 104 of theholding bell 102. The screw bolt 98 is connected, further, to the leafspring 92. If, then, a tension force higher than the tension force setas permissible on the leaf spring 92 occurs at the back bearer 6 a, thepretensioning spring 106 is compressed and the holding bell 102 isdisplaced on the screw bolt 98, with the result that a switch 112connected to the holding bell 102 is closed and transmits a fault signalto the control device 26 a.

FIGS. 10 and 11 show in detail the design of the thread tensioners 8 awhich are at the same time also configured as catch thread devices. Thethread tensioners 8 a are designed as drop wires and each have a guideorifice 114, by means of which they are mounted on a holder 116displaceably in the tensioning direction. The holders have a middlecontact part 118 which projects on one side and which, insulated, isembedded into lateral contact parts 120. The latter are connected to thesides of the guide orifice. In the event of a faulty warp tension, thethread tensioners 8 a are displaced by means of the pretensioning spring32 a until the contact parts 118, 120 of the holder 116 stand against anend face 124 of the guide orifice 114 and trigger a fault warning. Thethread tensioners lie in each case between two guide elements 30 a forthe warp thread 4 which is pieced up to the thread tensioners 8 a viarun-in eyes 34 a. On the side facing away from the pretensioning spring32 a, the thread tensioners each contain a grip part 126 with a signalpart 128 which projects out of the displacement plane of the threadtensioners, so that it is possible to detect those thread tensionerswhich indicate a broken warp thread and for this reason are no longer inalignment with the remaining signal parts 128. The signal part 128 isformed by a head part projecting out of the displacement plane.

List of reference symbols F₁ First shedding position F₂ Switchingposition F₃ Second shedding position H₁ Lift height of the 1st liftingdevice H₂ Lift height of the 2nd lifting device S Switching quantity αDeflection 2, 2a Warp let-off (warp beam) 4 Warp thread 6, 6a Backbearer 8, 8a Thread tensioner 10 Catch thread device 12, 12a Sheddingdevice 14 Shed 16 Weft thread 18 Beating-up edge 20 Cloth web 22 Clothholder 24, 24a Cloth take-up 26, 26a Control device 28, 28a Drive 29Braking device 30, 30a Guide element 32, 32a Pretensioning spring 34,34a Eye 36 Deflecting roller 38 First lifting device 40 Driver 40a Hook42 Lifting beam 44 Actuator 46 Control means 48 Second lifting device 50Control drop wire 52 Pretensioning spring 54 Lifting beam 56 Stop 58Hook part of 44 60 Hook part of 50 62 Driver slot 62a Driver slot 62bDriver slot 64 Control slot 66 Guide slot 68 Side wall 70 Side wall 72End wall 74 End wall 76 Run-on side 80 Cloth beam 82 Drive 84Selflocking gear 86 Tensioning spring device 88 Rocker 90 Supportingdevice 92 Leaf spring 94 Flexion converter 96 Safety device 98 Screwbolt 100 Head 102 Holding bell 104 Stop 106 Pretensioning spring 108Setscrew 110 Washer 112 Switch 114 Guide orifice 116 Holder 118 Contactpart 120 Lateral contact parts 124 End face 126 Grip part 128 Signalpart

1. A loom with a warp thread tensioning device and with a sheddingdevice which has warp threads pretensioned into a first sheddingposition, furthermore with a lifting device capable of being driven inoscillation and having drivers for the warp threads, and also withcontrol means actuable by means of actuators, in order to bring the warpthreads, and also with control means actuable by means of actuators, inorder to bring the warp threads selectively into engagement with thedrivers which move the warp threads into a second shedding position,wherein said loom has a second lifting device designed as a lifting beamcommon to all the warp threads, in order to move the warp threads out ofthe first shedding position into a switching position active for thefirst lifting device and in order to move nonselected warp threadsjointly into the first shedding position as a result of thepretensioning of the warp threads.
 2. The loom as claimed in claim 1,characterized in that the second lifting device executes at least halfof the lifting travel of the warp threads in the shed.
 3. The loom asclaimed in one of claims 1, characterized in that the first liftingdevice has, for each warp thread, a control drop wire with a driver slotand an assigned driver, preferably of hook-shaped design, for theassociated warp thread, the warp thread being capable of being broughtselectively into engagement with the driver by means of the control dropwire switchable by means of the actuator.
 4. The loom as claimed inclaim 3, characterized in that the driver slot is assigned to thedisplacement path of the driver and, in the switching region, leads, viaa control slot running obliquely with respect to the direction ofdisplacement of the driver, out of the displacement path of the driverinto a widened guide slot of the control drop wire.
 5. The loom asclaimed in claim 4, characterized in that the guide slot has a run-onside running toward the control slot.
 6. The loom as claimed in one ofclaim 3, characterized in that the control drop wire is designed in theform of a sleeve with two side walls, the driver being mounteddisplaceably between the side walls.
 7. The loom as claimed in claim 6,characterized in that at least the driver slot and the control slot areformed in the two side walls, the driver slots and the control slots ofthe side walls being offset relative to one another in the direction ofrun of the warp thread in such a way that a deflection of the runningwarp thread in the control drop wire is lower than 90°, preferably 10°.8. The loom as claimed in one of claim 3, characterized in that all thedrivers of a row can be moved up and down by means of a common liftingbeam.
 9. The loom as claimed in one of claim 1, characterized in thatthe warp thread tensioning device has an individual thread tensioner foreach warp thread on the run-in side of the warp threads to the sheddingdevice.
 10. The loom as claimed in claim 9, characterized in that thethread tensioner is designed as a catch thread device.
 11. The loom asclaimed in claim 9, characterized in that each warp thread is guided viatwo guide elements which are arranged at a distance from one another andbetween which is arranged the thread tensioner which engages on the warpthread and exerts a pretension on the warp thread.
 12. The loom asclaimed in claim 11, characterized in that the pretension is generatedby a tensioning weight.
 13. The loom as claimed in claim 11,characterized in that the pretension is generated by a tensioningspring.
 14. The loom as claimed in one of claim 9, characterized in thateach thread tensioner as a lateral run-in eye for the warp thread. 15.The loom as claimed in one of claim 9, characterized in that each threadtensioner has a guide orifice, by means of which it is mounted on aholder displaceably in the tensioning direction, the thread tensionerhaving, in the direction opposite to the pretensioning direction, a grippart which is provided with a signal part projecting out of thedisplacement direction.
 16. The loom as claimed in claim 15,characterized in that the holder has a middle contact part whichprojects from one side and which, insulated, is embedded into lateralcontact parts cooperating with the sides of the guide orifice of thethread tensioner, and, in the event of a faulty warp thread tension, thecontact parts can be bridged by means of an end face of the guideorifice for fault warning.
 17. The loom as claimed in one of claim 1,characterized in that the warp thread tensioning device has a controldevice which is connected to the drive of a cloth take-up, in order tocontrol the drive of the cloth take-up as a function of the retainingforce of a warp beam, in such a way that the warp threads as a whole areunder a predeterminable tension force.
 18. The loom as claimed in claim17, characterized in that, to generate the retaining force, the warpbeam has a specific drive provided with a selflocking gear.
 19. The loomas claimed in claim 17, characterized in that the warp thread tensioningdevice has a back bearer for the warp threads which is pretensioned bymeans of a tensioning spring device, the tensioning spring device beingconnected to the control device in such a way that the drives of thewarp beam and of the cloth take-up be controlled in such a way that thepredeterminable tension force can be maintained at the back bearer. 20.The loom as claimed in claim 19, characterized in that the tensioningspring device has a leaf spring with a flexion converter which isconnected to the control device.
 21. The loom as claimed in claim 19,characterized in that the tensioning spring device is connected to theback bearer via a safety device having an emergency switch whichresponds when the force of the warp threads which occurs at the backbearer is higher than the set tension force by a determinable safetyamount.